title: Diagnostic yield of oesophageal pH monitoring in patients with chronic unexplained cough.
abstract: OBJECTIVE
  One of the main causes of persistent cough is gastro-oesophageal reflux. In these patients, excessive oesophageal acid exposure and/or a temporal association between gastro-oesophageal reflux and cough can be demonstrated during 24-h pH monitoring. Impedance pH monitoring may have a higher yield than pH monitoring alone, but this technique is not yet widely available. The aim of this study was to assess the diagnostic yield of ambulatory 24-h oesophageal pH monitoring for the evaluation of chronic unexplained cough.
  
  
  METHODS
  Twenty-four-hour pH monitoring studies were analysed in 55 patients with chronic cough. In 14 of these studies concurrent ambulatory pressure monitoring was done. A cough episode was considered to be related to reflux if the cough occurred within two minutes after the onset of the reflux episode ("reflux-cough sequence"). Temporal relationships between cough and reflux were expressed by using the symptom association probability (SAP).
  
  
  RESULTS
  Thirty-seven patients actually coughed during the 24-h study. Eleven patients (20%) had a positive SAP for the reflux-cough sequence. In 5 patients, reflux followed coughing. Pathological oesophageal acid exposure was found in 15 subjects. Interestingly, only a minority (39.2%) of the cough bursts detected manometrically were marked by patients who had undergone both combined 24-h pH and pressure recording.
  
  
  CONCLUSIONS
  This study shows that, in a routine clinical setting, combined 24-h pH and pressure monitoring is useful in the evaluation of patients with chronic unexplained cough, as positive findings are not infrequently found and have diagnostic and therapeutic consequences.
authors.affiliation: Gastrointestinal Research Unit, Department of Gastroenterology, University Medical Centre, Utrecht, The Netherlands. a.bogte@umcutrecht.nl
authors.forename: Auke
authors.initials: A
authors.lastname: Bogte
authors.forename: Arjan J
authors.initials: AJ
authors.lastname: Bredenoord
authors.forename: André J P M
authors.initials: AJ
authors.lastname: Smout
mesh_terms: D000328:Adult; D002908:Chronic Disease; D003371:Cough / Q000209:etiology*; D004784:Environmental Monitoring; D004947:Esophagus; D005764:Gastroesophageal Reflux / Q000150:complications*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008365:Manometry; D012189:Retrospective Studies